Nick MoseyQueen's University | QueensU · Department of Chemistry
Nick Mosey
Doctor of Philosophy, University of Western Ontario, 2006
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56
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Introduction
We are a theoretical and computational chemistry research group at Queen's University, Kingston, ON, Canada.
Publications
Publications (56)
Electronic structure calculations representing the molecular orbitals (MOs) with contracted planewave basis functions (CPWBFs) have been reported recently. CPWBFs are Fourier‐series representations of atom‐centered basis functions. The mathematical features of CPWBFs permit the construction of matrix–vector products, FC o, involving the application...
First-principles molecular dynamics (FPMD) simulations are used to investigate the chemical response of thioaldehyde (MeCHS) to compression between (001) surfaces of magnesium oxide (MgO), with the external load reaching values as high as 20 GPa. The results demonstrate that the application of a load transforms the MeCHS molecules into oligomers th...
Ways to reduce the computational cost of periodic electronic structure calculations by using basis functions corresponding to linear combinations of planewaves have been examined recently. These contracted planewave (CPW) basis functions correspond to Fourier series representations of atom‐centered basis functions, and thus provide access to some b...
The evaluation of exact exchange (EXX) is an important component of quantum chemical calculations performed with ab initio and hybrid density functional methods. While evaluating exact exchange is routine in molecular quantum chemical calculations performed with localized basis sets, the non-local nature of the exchange operator presents a major im...
First-principles molecular dynamics simulations are used to investigate the chemical behavior of bulk thioacetaldehyde (MeC(H)S) in response to changes in pressure, P. The simulations show that these molecules oligomerize in response to applied P. Oligomerization is initiated through C—S bond formation, with constrained dynamics simulations showing...
The interaction between carbon dioxide (CO2) and amidines such as 1,8-diazabicyclo[5.4.0]undecane (DBU) has been extensively studied, but the reaction of isovalent CS2 with such bases has been largely ignored, apart from a single crystallography report. Acyclic acetamidines are cleaved by CS2 at room temperature to give an isothiocyanate and a thio...
With its facile synthesis, the pyridine-1,2,3-triazole chelate is an attractive building block for coordination-driven self-assembly. When two such chelates are bridged by a spacer and exposed to cations of octahedral geometrical preference, they generally self-assemble into dinuclear triple-stranded structures in the solid state and in solution in...
Two sterically equivalent series of phenoxy-terminated 5-alkoxy-2-(4-alkoxyphenyl)pyrimidine liquid crystals were synthesised, and their mesogenic properties were characterised by polarised optical microscopy and differential scanning calorimetry (DSC). The phenoxy end-group causes a significant increase in melting point and inhibits – at least par...
Density functional theory calculations were performed for the methanolysis reactions of a set of aryloxy and alkoxy acetates (1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j, 1k, 1l, 1m) promoted by methoxide and a 1,5,9-triazacyclododecane-complexed Zn(II)-methoxide [2(OCH3)]+ in order to give free energies and structural data for the various intermediates...
A density functional theory study of the cleavage of a DNA model [p-nitrophenyl methyl phosphate (2)] and two RNA models [p-nitrophenyl 2-hydroxypropyl phosphate (3) and phenyl 2-hydroxypropyl phosphate (4)] promoted by the dinuclear Zn-(II) complex of 1,3-bis(1,5,9triazacyclododec-1-yl)propane formulated with a bridging methoxide (la) was undertak...
The new N,C-chelate boron compounds B(2-phenylazolyl)Mes [Mes = mesityl; azolyl = benzothiazolyl (1a), 4-methylthiazolyl (2a), benzoxazolyl (3a), benzimidazolyl (4a)] undergo an unprecedented multistructural transformation upon light irradiation or heating, sequentially producing isomers b, c, d, and e. The dark isomers b generated by photoisomeriz...
The partial positive charge of amide protons is used to promote macrocyclization and form crown-ether analogs. Their deprotonation generates very selective pH-switchable alkaline earth ion receptors only in the presence of an appropriate substrate.
C,C-chelate dimesitylboron (BMes(2)) compounds containing an N-heterocyclic carbene (NHC) donor have been obtained. Single-crystal X-ray diffraction analyses established that the boron atom in these compounds is bound by four carbon atoms in a distorted tetrahedral geometry. Compared to previously reported N,C-chelate dimesitylboron compounds, the...
The base‐promoted solvolysis of a series of O,O‐dimethyl O‐aryl and O,O‐dimethyl O‐alkyl phosphorothioates (1) as well as O,O‐dimethyl O‐aryl and O,O‐dimethyl O‐alkyl phosphates (2) was studied computationally by density functional theory methods in methanol and water continuum media to determine the transition between concerted and stepwise proces...
How easily can ions move in DNA channels? Three-dimensional free-energy landscapes for the movement of Na(+) , K(+) , and NH(4) (+) ions through G-quadruplex DNA channels have been obtained by molecular dynamics simulations. The computed results are in qualitative agreement with the limited experimental data: large K(+) and NH(4) (+) ions squeeze t...
An experimental determination of the βEq value for equilibrium transfer of the O,O‐dimethyl phosphorothioyl group between oxyanion nucleophiles in water and methanol at 25 °C is presented. The respective βEq values in the two solvents are experimentally the same at −1.45 ± 0.08 and −1.39 ± 0.12. Based on the observation that the Brønsted correlatio...
Mechanochemistry, the use of mechanical stresses to activate chemical reactions, has emerged as a topic of significant interest. The present study examines the use of an approximate model for the prediction of reaction barriers under mechanochemical conditions using the ring opening of 1,3-cyclohexadiene along conrotatory and disrotatory directions...
First-principles molecular dynamics (FPMD) simulations and static quantum chemical (QC) calculations are used to evaluate the tensile strengths, σ(c), of interfaces consisting of (0001) surfaces of α-Al(2)O(3) separated by small organic species. The evaluation of σ(c) with FPMD was achieved by performing simulations in which the simulation cell was...
First-principles molecular dynamics (FPMD) simulations are used to explore the tribological behavior of systems consisting of two Al2O3 (0001) surfaces separated by acetaldehyde molecules. The simulations were performed with normal pressures, P, that ranged from 0 to 20 GPa. The simulations show that sliding occurs with little or no significant cha...
Palladacycle 1 catalyzes the methanolytic cleavage of N-methyl-N-(4-nitrophenyl)thiobenzamide (4) via a mechanism involving formation of a Pd-bound tetrahedral intermediate (TI). The rate constant for decomposition of the complex formed between 1, methoxide, and 4 is 9.3 s(-1) at 25 °C; this reaction produces methyl thiobenzoate and N-methyl-4-nitr...
An approach termed temporal quantum mechanics/molecular mechanics is presented to extend the time scales accessible in molecular dynamics simulations of reactions. This approach employs a hierarchy of methods: force-fields (FFs) to simulate the system near potential energy minima, semi-empirical (SE) molecular orbital methods to assess the likeliho...
N,N'-Disubstituted formamidines, and amidines in general, have very rich configurational, conformational, and tautomeric diversities. As part of an effort to incorporate alkoxyamine-derived formamidine units into foldamers, the first evidence for the isolation of the up-to-now unknown E isomer, the conditions for its exclusive formation, its stabil...
N-H-containing formamidines combine a reasonably strong association to carboxylic acids to form complexes of well-defined geometries with a simultaneous proton-induced electrophilicity enhancement that allows for the exchange of their amine portion. The N=C(H)-NH fragment, therefore, undergoes "imine-like" exchange with N-containing nucleophiles. B...
The 1,3-dipolar cycloaddition reaction of cyclopropanes and nitrones to give tetrahydro-1,2-oxazine has been studied with density functional theory calculations at the B3LYP/6-31+G(d,p) level of theory. Realistic substituents were modelled including those at the 2-, 3-, 4-, and 6-positions of the final oxazine ring product. The strained σ bond of t...
First-principles molecular dynamics simulations are used to investigate the chemical response of acetaldehyde molecules (MeCHO) to compression and decompression between (0001) surfaces of α-alumina (Al(2)O(3)), with pressures reaching approximately 40 GPa. The results demonstrate that the MeCHO molecules are transformed into other chemical species...
Stresstest: Quantenchemische Studien darüber, wie Moleküle, die mechanischem Stress ausgesetzt werden (siehe Bild; Fext ist eine externe Kraft), die Woodward-Hoffmann(WH)-Regeln überwinden können, ergaben, dass mechanischer Stress nicht die elektronische Struktur des Moleküls ändert (wie es bei einer Bestrahlung der Fall wäre), sondern dass mechano...
The methanolytic cleavage of a series of O,O-dimethyl O-aryl phosphorothioates (1a−g) catalyzed by a C,N-palladacycle, (2-[N,N-dimethylamino(methyl)phenyl]-C1,N)(pyridine) palladium(II) triflate (3), at 25 °C and sspH 11.7 in methanol is reported, along with data for the methanolytic cleavage of 1a−g. The methoxide reaction gives a linear log k2−OM...
First-principles molecular dynamics simulations are used to explore sliding along interfaces composed of different forms of hydroxylated (0001)/(0001) interfaces of α-alumina (Al2O3). The results demonstrate that a fully hydroxylated form of the interface is insensitive to changes in normal pressure, P. Meanwhile, partially hydroxylated interfaces...
First-principles molecular dynamics (FPMD) simulations were used to study static friction, Fs, using model systems based on bulk and hydroxylated forms of Al2O3. The results demonstrate that Fs is significantly affected by adhesive interactions and by changes in the numbers of those interactions through the formation and dissociation of bonds acros...
First-principles molecular dynamics simulations are used to investigate the behavior of bulk acetaldehyde (MeCHO) under conditions of increasing pressure. The results demonstrate that increasing pressure causes the aldehydes to polymerize, yielding polyethers through a process involving the rapid formation of C-O bonds between multiple neighboring...
A method for predicting the shear strength of materials over multiple length scales is developed and tested. The method is based on renormalizing the energies and shear displacements obtained through electronic structure calculations of nanoscale models of the material of interest. All material- and size-dependent quantities are incorporated into t...
In this study we present x-ray diffraction data on metal phosphates containing either high or low coordination number zinc or calcium. The experiments reveal that low-coordination zinc phosphate crystals are relatively soft at ambient conditions but stiffen dramatically with pressure, p, thereby exhibiting smart materials behavior. In comparison, h...
Periodic density functional theory (DFT) and DFT+U calculations are used to evaluate various mechanical properties associated with the fracture of chromia (Cr2O3) along the [0 0 0 1] and directions. The properties investigated include the tensile strength, elastic constants, and surface energies. The tensile strengths are evaluated using an ideal t...
Chiral mesoporous materials have been prepared with purely organic monomers employing an enantiomerically pure biphenyl bis-siloxane as a dopant along with simple 4,4'-bis(triethoxysilyl)biphenyl as the bulk material. Analysis of these materials by CD spectroscopy indicates the formation of new chiral aggregates in the solid state consistent with c...
Conventional density functional theory (DFT) fails for strongly correlated electron systems due to large intra-atomic self-interaction errors. The DFT+U method provides a means of overcoming these errors through the use of a parametrized potential that employs an exact treatment of quantum mechanical exchange interactions. The parameters that enter...
A recently suggested mechanism for the stress memory of various metal phosphates is investigated experimentally. Based on first-principles simulations [
N. J. Mosey et al., Science 307, 1612 (2005)
], it had been argued that atoms with flexible coordination, such as zinc or heavy-metal cations, act as network-forming agents, undergoing irreversible...
Conventional density functional theory (DFT) fails for materials with
strongly correlated electrons, such as late transition metal oxides.
Large errors in the intra-atomic Coulomb and exchange interactions are
the source of this failure. The DFT+U method has provided a means,
through empirical parameters, to correct these errors. Here, we present
a...
Experiments are described where the experimental conditions have been optimized to detect aspirin by MALDI mass spectrometry. Although protonated aspirin was not observed by MALDI, sodium and potassium aspirin adducts could be found. Significantly better signals could be obtained by using Rb and Cs salts as cationization sources. Quantum calculatio...
Assigning effective atomic charges that properly reproduce the electrostatic fields of molecules is a crucial step in the construction of accurate interatomic potentials. We propose a new approach to calculate these charges, which as previous approaches are, is based on the idea of charge equilibration. However, we only allow charge to flow between...
The reactions that occur between metathiophosphate (MTP) molecules are identified and examined through ab initio molecular dynamics simulations and static quantum chemical calculations at the density functional level of theory. The simulations show that certain types of MTPs can react to yield phosphate chains, while others only dimerize. These dif...
Ab initio molecular dynamics simulations and static quantum chemical calculations at the density functional level of theory have been applied to study zinc dialkyldithiophosphate (ZDDP) engine oil anti-wear additives in their parent, isomeric and decomposed forms to identify differences in the basic finite temperature chemical behavior of these spe...
Charge-equilibration (C-Eq) methods are an efficient means of calculating the effective partial charges of the atoms in molecules. The aim of obtaining the partial charges is to reconstruct the electrostatic field of a molecule, which then may be used as an accurate replacement to ab initio interatomic potentials. However, the inability of the C-Eq...
The interactions between metathiophosphates (MTPs) and zinc dialkyldithiophosphates (ZnDDPs) were explored through molecular simulation. The results highlight a novel reaction leading to the formation of zinc phosphate polymers and networks through the insertion of MTPs into ZnDDPs.
The chemomechanical response of tri-phosphates (TPs) and zinc phosphates (ZPs) to changes in pressure p and temperature T is studied through first principle molecular dynamics. The maximum values of p (> 20 GPa) and T (≈ 1, 000 K) are chosen to mimic roughly the extreme conditions to which phosphates may be exposed during their role as engine anti-...
The quantum chemical simulations of zinc phosphates (ZP) exposed to time-dependent external pressure to gain insight into the performance of zinc dialkyldithiophosphates (ZDDP), were analyzed. The simulations revealed that pressure induced cross-link formation is a fundamental process in both the formation of the anti-wear (AW) films and the inhibi...
A molecular level theory of the formation and function of zinc dialkyldithiophosphates (ZDDP) AW films, were analyzed. The theory is based on the the notion that pressure-induced crosslinking alters the chemical and mechanical properties of the films such that their AW properties are enhanced. The pressure to which the film is exposed, depends on t...
Wear limits the life-span of many mechanical devices with moving parts. To reduce wear, lubricants are frequently enriched
with additives, such as zinc phosphates, that form protective films on rubbing surfaces. Using first-principles molecular
dynamics simulations of films derived from commercial additives, we unraveled the molecular origin of how...
We review a recently developed molecular-level theory for the formation and functionality of zinc dialkyldithiophos-phate anti-wear films [N. J. Mosey, M. H. Müser and T. K. Woo, Science 307 (2005) 1612]. This theory is based on the idea that pressure-induced cross-linking leads to chemically connected networks. The formation of cross-links modifie...
Wear limits the lifespan of many mechanical devices with moving parts. To reduce wear, lubricants are frequently enriched with additives that form protective pads on rubbing surfaces. With first-principles molecular dynamics simulations of pads derived from commercial additives, namely zinc-phosphates, we unravel the molecular origin of how anti-we...
The neutral vapors above liquid alcohol/ether mixtures, (diethyl ether/methanol, diethyl ether/ethanol, tetrahydrofuran/methanol, and tetrahydrofuran/ethanol) were co-expanded with He in a supersonic jet, ionized with a 118-nm vacuum ultraviolet laser, and detected in a time-of-flight mass spectrometer. In each case, features attributed to protonat...
Density functional theory calculations were applied to study a set of isomerization and decomposition reactions that zinc dialkyldithiophosphate (ZDDP) engine oil antiwear additives may take part in. The products of these reactions comprise a set of chemical species that can lead to the formation of poly(thio)phosphate films that are thought to be...
The thermal decomposition of several zinc dialkyldithiophosphate (ZDDP) antiwear additives has been explored with both finite temperature gas-phase ab initio molecular dynamics (MD) simulations and static quantum chemical calculations at the density functional (DFT) level of theory. Calculations have been performed on the ZDDP monomers (Zn(S2P(OR)2...
A method for promoting reaction events in ab initio molecular dynamics simulations that is explicitly based on the electronic structure is developed. The technique uses a bias potential that is added to the regular potential and is constructed from the HOMO–LUMO gap of the system. This bias potential is tested along predetermined reaction coordinat...
The mechanism of the addition of nonenolizable aldehydes and ketones to group 14 (di)metallenes has been examined through a theoretical study of the addition of formaldehyde to Si=C, Ge=C, Si=Si, Si=Ge, and Ge=Ge bonds at the B3LYP/6-311++G(d,p) and CAS-MCQDPT2/6-31++G(d,p) levels of theory. The reaction pathways located can be grouped as either in...